Low cost disposable digital instant printing camera system

ABSTRACT

A handheld camera system comprising: a core chassis; an ink cartridge unit including an ink supply and print head unit, the ink cartridge unit being mounted on the chassis; a roll of print media rotatably mounted between end portions of the chassis, the print head unit being adapted to print on the print media; a platten unit including mounted below the print head unit; image sensor and control circuitry interconnected to the print head unit and adapted to sense an image for printing by the print head unit; an outer casing for enclosing the chassis, ink cartridge unit, the print media, the platten unit and the circuitry. The camera system further comprises a cutting unit adapted to traverse the print media so as to separate the print media into separate images. The cutting unit can be mounted on the platten unit and the platten unit can further include a print head recapping unit for capping the print head when not in use. The camera system can further comprise a series of pinch rollers for decurling the print media.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are hereby incorporated by cross-reference. For the purposes of location and identification, U.S. patent applications identified by their U.S. patent application serial numbers (USSN) are listed alongside the Australian applications from which the U.S. patent applications claim the right of priority.

CROSS-REFERENCED U.S. patent application AUSTRALIAN (CLAIMING RIGHT OF PROVISIONAL PRIORITY FROM AUSTRALIAN DOCKET PATENT NO. PROVISIONAL APPLICATION) NO. PO7991 09/113,060 ART01 PO8505 09/113,070 ART02 PO7988 09/113,073 ART03 PO9395 09/112,748 ART04 PO8017 09/112,747 ART06 PO8014 09/112,776 ART07 PO8025 09/112,750 ART08 PO8032 09/112,746 ART09 PO7999 09/112,743 ART10 PO7998 09/112,742 ART11 PO8031 09/112,741 ART12 PO8030 09/112,740 ART13 PO7997 09/112,739 ART15 PO7979 09/113,053 ART16 PO8015 09/112,738 ART17 PO7978 09/113,067 ART18 PO7982 09/113,063 ART19 PO7989 09/113,069 ART20 PO8019 09/112,744 ART21 PO7980 09/113,058 ART22 PO8018 09/112,777 ART24 PO7938 09/113,224 ART25 PO8016 09/112,804 ART26 PO8024 09/112,805 ART27 PO7940 09/113,072 ART28 PO7939 09/112,785 ART29 PO8501 09/112,797 ART30 PO8500 09/112,796 ART31 PO7987 09/113,071 ART32 PO8022 09/112,824 ART33 PO8497 09/113,090 ART34 PO8020 09/112,823 ART38 PO8023 09/113,222 ART39 PO8504 09/112,786 ART42 PO8000 09/113,051 ART43 PO7977 09/112,782 ART44 PO7934 09/113,056 ART45 PO7990 09/113,059 ART46 PO8499 09/113,091 ART47 PO8502 09/112,753 ART48 PO7981 09/113,055 ART50 PO7986 09/113,057 ART51 PO7983 09/113,054 ART52 PO8026 09/112,752 ART53 PO8027 09/112,759 ART54 PO8028 09/112,757 ART56 PO9394 09/112,758 ART57 PO9396 09/113,107 ART58 PO9397 09/112,829 ART59 PO9398 09/112,792 ART60 PO9399 09/112,791 ART61 PO9400 09/112,790 ART62 PO9401 09/112,789 ART63 PO9402 09/112,788 ART64 PO9403 09/112,795 ART65 PO9405 09/112,749 ART66 PP0959 09/112,784 ART68 PP1397 09/112,783 ART69 PP2370 09/112,781 DOT01 PP2371 09/113,052 DOT02 PO8003 09/112,834 Fluid01 PO8005 09/113,103 Fluid02 PO9404 09/113,101 Fluid03 PO8066 09/112,751 IJ01 PO8072 09/112,787 IJ02 PO8040 09/112,802 IJ03 PO8071 09/112,803 IJ04 PO8047 09/113,097 IJ05 PO8035 09/113,099 IJ06 PO8044 09/113,084 IJ07 PO8063 09/113,066 IJ08 PO8057 09/112,778 IJ09 PO8056 09/112,779 IJ10 PO8069 09/113,077 IJ11 PO8049 09/113,061 IJ12 PO8036 09/112,818 IJ13 PO8048 09/112,816 IJ14 PO8070 09/112,772 IJ15 PO8067 09/112,819 IJ16 PO8001 09/112,815 IJ17 PO8038 09/113,096 IJ18 PO8033 09/113,068 IJ19 PO8002 09/113,095 IJ20 PO8068 09/112,808 IJ21 PO8062 09/112,809 IJ22 PO8034 09/112,780 IJ23 PO8039 09/113,083 IJ24 PO8041 09/113,121 IJ25 PO8004 09/113,122 IJ26 PO8037 09/112,793 IJ27 PO8043 09/112,794 IJ28 PO8042 09/113,128 IJ29 PO8064 09/113,127 IJ30 PO9389 09/112,756 IJ31 PO9391 09/112,755 IJ32 PP0888 09/112,754 IJ33 PP0891 09/112,811 IJ34 PP0890 09/112,812 IJ35 PP0873 09/112,813 IJ36 PP0993 09/112,814 IJ37 PP0890 09/112,764 IJ38 PP1398 09/112,765 IJ39 PP2592 09/112,767 IJ40 PP2593 09/112,768 IJ41 PP3991 09/112,807 IJ42 PP3987 09/112,806 IJ43 PP3985 09/112,820 IJ44 PP3983 09/112,821 IJ45 PO7935 09/112,822 IJM01 PO7936 09/112,825 IJM02 PO7937 09/112,826 IJM03 PO8061 09/112,827 IJM04 PO8054 09/112,828 IJM05 PO8065 09/113,111 IJM06 PO8055 09/113,108 IJM07 PO8053 09/113,109 IJM08 PO8078 09/113,123 IJM09 PO7933 09/113,114 IJM10 PO7950 09/113,115 IJM11 PO7949 09/113,129 IJM12 PO8060 09/113,124 IJM13 PO8059 09/113,125 IJM14 PO8073 09/113,126 IJM15 PO8076 09/113,119 IJM16 PO8075 09/113,120 IJM17 PO8079 09/113,221 IJM18 PO8050 09/113,116 IJM19 PO8052 09/113,118 IJM20 PO7948 09/113,117 IJM21 PO7951 09/113,113 IJM22 PO8074 09/113,130 IJM23 PO7941 09/113,110 IJM24 PO8077 09/113,112 IJM25 PO8058 09/113,087 IJM26 PO8051 09/113,074 IJM27 PO8045 09/113,089 IJM28 PO7952 09/113,088 IJM29 PO8046 09/112,771 IJM30 PO9390 09/112,769 IJM31 PO9392 09/112,770 IJM32 PP0889 09/112,798 IJM35 PP0887 09/112,801 IJM36 PP0882 09/112,800 IJM37 PP0874 09/112,799 IJM38 PP1396 09/113,098 IJM39 PP3989 09/112,833 IJM40 PP2591 09/112,832 IJM41 PP3990 09/112,831 IJM42 PP3986 09/112,830 IJM43 PP3984 09/112,836 IJM44 PP3982 09/112,835 IJM45 PP0895 09/113,102 IR01 PP0870 09/113,106 IR02 PP0869 09/113,105 IR04 PP0887 09/113,104 IR05 PP0885 09/112,810 IR06 PP0884 09/112,766 IR10 PP0886 09/113,085 IR12 PP0871 09/113,086 IR13 PP0876 09/113,094 IR14 PP0877 09/112,760 IR16 PP0878 09/112,773 IR17 PP0879 09/112,774 IR18 PP0883 09/112,775 IR19 PP0880 09/112,745 IR20 PP0881 09/113,092 IR21 PO8006 09/113,100 MEMS02 PO8007 09/113,093 MEMS03 PO8008 09/113,062 MEMS04 PO8010 09/113,064 MEMS05 PO8011 09/113,082 MEMS06 PO7947 09/113,081 MEMS07 PO7944 09/113,080 MEMS09 PO7946 09/113,079 MEMS10 PO9393 09/113,065 MEMS11 PP0875 09/113,078 MEMS12 PP0894 09/113,075 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates substantially to the concept of a disposable camera having instant printing capabilities and in particular, discloses a low cost disposable camera system.

BACKGROUND OF THE INVENTION

Recently, the concept of a “single use” disposable camera has become an increasingly popular consumer item. Disposable camera systems presently on the market normally include an internal film roll and a simplified gearing mechanism for traversing the film roll across an imaging system including a shutter and lensing system. The user, after utilising a single film roll returns the camera system to a film development centre for processing. The film roll is taken out of the camera system and processed and the prints returned to the user. The camera system is then able to be re-manufactured through the insertion of a new film roll into the camera system, the replacement of any worn or wearable parts and the re-packaging of the camera system in accordance with requirements. In this way, the concept of a single use “disposable” camera is provided to the consumer.

Recently, a camera system has been proposed by the present applicant which provides for a handheld camera device having an internal print head, image sensor and processing means such that images sense by the image sensing means, are processed by the processing means and adapted to be instantly printed out by the printing means on demand. The proposed camera system further discloses a system of internal “print rolls” carrying print media such as film on to which images are to be printed in addition to ink for supplying to the printing means for the printing process. The print roll is further disclosed to be detachable and replaceable within the camera system.

Unfortunately, such a system is likely to only be constructed at a substantial cost and it would be desirable to provide for a more inexpensive form of instant camera system which maintains a substantial number of the quality aspects of the aformentioned arrangement.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide for the efficient and effective one time use disposable camera system.

In accordance with a first aspect of the present invention, there is provided a handheld camera system comprising: a core chassis; an ink cartridge unit including an ink supply and print head unit, the ink cartridge unit being mounted on the chassis; a roll of print media rotatably mounted between end portions of the chassis, the print head unit being adapted to print on the print media; a platten unit mounted below the print head unit; image sensor and control circuitry interconnected with the print head unit and adapted to sense an image for printing by the print head unit; an outer casing for enclosing the chassis, ink cartridge unit, the print media, the platten unit and the circuitry.

Preferably, the camera system further comprises a cutting unit adapted to traverse the print media so as to separate the print media into separate images. The cutting unit can be mounted on the platten unit and the platten unit can further include a print head recapping unit for capping the print head when not in use.

The camera system can further comprise a series of pinch rollers for decurling the print media.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 illustrates a front perspective view of the assembled camera of the preferred embodiment;

FIG. 2 illustrates a rear perspective view, partly exploded, of the preferred embodiment;

FIG. 3 is a perspective view of the chassis of the preferred embodiment;

FIG. 4 is a perspective view of the chassis illustrating mounting of electric motors;

FIG. 5 is an exploded perspective view of the ink supply mechanism of the preferred embodiment;

FIG. 6 is a rear perspective view of the assembled form of the ink supply mechanism of the preferred embodiment;

FIG. 7 is a front perspective view of the assembled form of the ink supply mechanism of the preferred embodiment;

FIG. 8 is an exploded perspective view of the platten unit of the preferred embodiment;

FIG. 9 is a perspective view of the assembled form of the platten unit;

FIG. 10 is also a perspective view of the assembled form of the platten unit;

FIG. 11 is an exploded perspective view of the printhead recapping mechanism of the preferred embodiment;

FIG. 12 is a close up exploded perspective view of the recapping mechanism of the preferred embodiment;

FIG. 13 is an exploded perspective view of the ink supply cartridge of the preferred embodiment;

FIG. 14 is a close up perspective view, partly in section, of the internal portions of the ink supply cartridge in an assembled form;

FIG. 15 is a schematic block diagram of one form of chip layer of the image capture and processing chip of the preferred embodiment;

FIG. 16 is an exploded perspective view illustrating the assembly process of the preferred embodiment;

FIG. 17 illustrates a front exploded perspective view of the assembly process of the preferred embodiment;

FIG. 18 illustrates a perspective view of the assembly process of the preferred embodiment;

FIG. 19 illustrates a perspective view of the assembly process of the preferred embodiment;

FIG. 20 is a perspective view illustrating the insertion of the platten unit in the preferred embodiment;

FIG. 21 illustrates the interconnection of the electrical components of the preferred embodiment;

FIG. 22 illustrates the process of assembling the preferred embodiment; and

FIG. 23 is a perspective view further illustrating the assembly process of the preferred embodiment.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Turning initially simultaneously to FIG. 1 and FIG. 2 there are illustrated perspective views of an assembled camera constructed in accordance with the preferred embodiment with FIG. 1 showing a front perspective view and FIG. 2 showing a rear perspective view. The camera 1 includes a paper or plastic film jacket 2 which can include simplified instructions 3 for the operation of the camera system 1. The camera system 1 includes a first “take” button 4 which is depressed to capture an image. The captured image is output via output slot 6. A further copy of the image can be obtained through depressing a second “printer copy” button 7 whilst an LED light 5 is illuminated. The camera system also provides the usual view finder 8 in addition to a CCD image capture/lensing system 9.

The camera system 1 provides for a standard number of output prints after which the camera system 1 ceases to function. A prints left indicator slot 10 is provided to indicate the number of remaining prints. A refund scheme at the point of purchase is assumed to be operational for the return of used camera systems for recycling.

Turning now to FIG. 3, the assembly of the camera system is based around an internal chassis 12 which can be a plastic injection molded part. A pair of paper pinch rollers 28, 29 utilized for decurling are snap fitted into corresponding frame holes eg. 26, 27.

As shown in FIG. 4, the chassis 12 includes a series of mutually opposed prongs eg. 13, 14 into which is snapped fitted a series of electric motors 16, 17. The electric motors 16, 17 can be entirely standard with the motor 16 being of a stepper motor type. The motors 16, 17 include cogs 19, 20 for driving a series of gear wheels. A first set of gear wheels is provided for controlling a paper cutter mechanism and a second set is provided for controlling print roll movement.

Turning next to FIGS. 5 to 7, there is illustrated an ink supply mechanism 40 utilized in the camera system. FIG. 5 illustrates a rear exploded perspective view, FIG. 6 illustrates a rear assembled perspective view and FIG. 7 illustrates a front assembled view. The ink supply mechanism 40 is based around an ink supply cartridge 42 which contains printer ink and a print head mechanism for printing out pictures on demand. The ink supply cartridge 42 includes a side aluminium strip 43 which is provided as a shear strip to assist in cutting images from a paper roll.

A dial mechanism 44 is provided for indicating the number of “prints left”. The dial mechanism 44 is snap fitted through a corresponding mating portion 46 so as to be freely rotatable.

As shown in FIG. 6, the mechanism 40 includes a flexible PCB strip 47 which interconnects with the print head and provides for control of the print head. The interconnection between the Flex PCB strip and an image sensor and print head chip can be via Tape Automated Bonding (TAB) strips 51, 58. A moulded aspherical lens and aperture shim 50 (FIG. 5) is also provided for imaging an image onto the surface of the image sensor chip normally located within cavity 53 and a light box module or hood 52 is provided for snap fitting over the cavity 53 so as to provide for proper light control. A series of decoupling capacitors eg. 34 can also be provided. Further a plug 45 (FIG. 7) is provided for re-plugging ink holes after refilling. A series of guide prongs eg. 55-57 are further provided for guiding the flexible PCB strip 47.

The ink supply mechanism 40 interacts with a platten unit 60 which guides print media under a printhead located in the ink supply mechanism. FIG. 8 shows an exploded view of the platten unit 60, while FIGS. 9 and 10 show assembled views of the platten unit. The platten unit 60 includes a first pinch roller 61 which is snap fitted to one side of a platten base 62. Attached to a second side of the platten base 62 is a cutting mechanism 63 which traverses the platten unit 60 by means of a rod 64 having a screw thread which is rotated by means of cogged wheel 65 which is also fitted to the platten base 62. The screw threaded rod 64 mounts a block 67 which includes a cutting wheel 68 fastened via a fastener 69. Also mounted to the block 67 is a counter actuator which includes a pawl 71. The pawl 71 acts to rotate the dial mechanism 44 of FIG. 6 upon the return traversal of the cutting wheel. As shown previously in FIG. 6, the dial mechanism 44 includes a cogged surface which interacts with pawl 71, thereby maintaining a count of the number of photographs by means of numbers embossed on the surface of dial mechanism 44. The cutting mechanism 63 is inserted into the platten base 62 by means of a snap fit via clips. 74.

The platten unit 60 includes an internal recapping mechanism 80 for recapping the print head when not in use. The recapping mechanism 80 includes a sponge portion 81 and is operated via a solenoid coil so as to provide for recapping of the print head. In the preferred embodiment, there is provided an inexpensive form of printhead re-capping mechanism provided for incorporation into a handheld camera system so as to provide for printhead re-capping of an inkjet printhead.

FIG. 11 illustrates an exploded view of the recapping mechanism whilst FIG. 12 illustrates a close up of the end portion thereof. The re-capping mechanism 80 is structured around a solenoid including a 16 turn coil 75 which can comprise insulated wire. The coil 75 is turned around a first stationery solenoid arm 76 which is mounted on a bottom surface of the platten base 62 (FIG. 8) and includes a post portion 77 to magnify effectiveness of operation. The arm 76 can comprise a ferrous material.

A second moveable arm 78 of the solenoid actuator is also provided. The arm 78 is moveable and is made of ferrous material. Mounted on the arm is a sponge portion surrounded by an elastomer strip 79. The elastomer strip 79 is of a generally arcuate cross-section and act as a leaf spring against the surface of the printhead ink supply cartridge 42 (FIG. 5) so as to provide for a seal against the surface of the printhead ink supply cartridge 42. In the quiescent position a elastomer spring unit 87, 88 acts to resiliently deform the elastomer seal 79 against the surface of the ink supply unit 42.

When it is desired to operate the printhead unit, upon the insertion of paper, the solenoid coil 75 is activated so as to cause the arm 78 to move down to be adjacent to the end plate 76. The arm 78 is held against end plate 76 while the printhead is printing by means of a small “keeper current” in coil 75. Simulation results indicate that the keeper current can be significantly less than the actuation current. Subsequently, after photo printing, the paper is guillotined by the cutting mechanism 63 of FIG. 8 acting against Aluminium Strip 43, and rewound so as to clear the area of the re-capping mechanism 80. Subsequently, the current is turned off and springs 87, 88 return the arm 78 so that the elastomer seal is again resting against the printhead ink supply cartridge.

It can be seen that the preferred embodiment provides for a simple and inexpensive means of re-capping a printhead through the utilisation of a solenoid type device having a long rectangular form. Further, the preferred embodiment utilises minimal power in that currents are only required whilst the device is operational and additionally, only a low keeper current is required whilst the printhead is printing.

Turning next to FIG. 13 and 14, FIG. 13 illustrates an exploded perspective of the ink supply cartridge 42 whilst FIG. 14 illustrates a close up sectional view of a bottom of the ink supply cartridge with the printhead unit in place. The ink supply cartridge 42 is based around a pagewidth printhead 102 which comprises a long slither of silicon having a series of holes etched on the back surface for the supply of ink to a front surface of the silicon wafer for subsequent ejection via a micro electro mechanical system. The form of ejection can be many different forms such as those set out in the tables below.

Of course, many other inkjet technologies, as referred to the attached tables below, can also be utilised when constructing a printhead unit 102. The fundamental requirement of the ink supply cartridge 42 is the supply of ink to a series of colour channels etched through the back surface of the printhead 102. In the description of the preferred embodiment, it is assumed that a three colour printing process is to be utilised so as to provide full colour picture output. Hence, the print supply unit includes three ink supply reservoirs being a cyan reservoir 104, a magenta reservoir 105 and a yellow reservoir 106. Each of these reservoirs is required to store ink and includes a corresponding sponge type material 107-109 which assists in stabilising ink within the corresponding ink channel and inhibiting the ink from sloshing back and forth when the printhead is utilised in a handheld camera system. The reservoirs 104, 105, 106 are formed through the mating of first exterior plastic piece 110 and a second base piece 111.

At a first end 118 of the base piece 111 a series of air inlet 113-115 are provided. Each air inlet leads to a corresponding winding channel which is hydrophobically treated so as to act as an ink repellent and therefore repel any ink that may flow along the air inlet channel. The air inlet channel further takes a convoluted path assisting in resisting any ink flow out of the chambers 104-106. An adhesive tape portion 117 is provided for sealing the channels within end portion 118.

At the top end, there is included a series of refill holes (not shown) for refilling corresponding ink supply chambers 104, 105, 106. A plug 121 is provided for sealing the refill holes.

Turning now to FIG. 14, there is illustrated a close up perspective view, partly in section through the ink supply cartridge 42 of FIG. 13 when formed as a unit. The ink supply cartridge includes the three colour ink reservoirs 104, 105, 106 which supply ink to different portions of the back surface of printhead 102 which includes a series of apertures 128 defined therein for carriage of the ink to the front surface.

The ink supply cartridge 42 includes two guide walls 124, 125 which separate the various ink chambers and are tapered into an end portion abutting the surface of the printhead 102. The guide walls 124, 125 are further mechanically supported by block portions eg. 126 which are placed at regular intervals along the length of the ink supply unit. The block portions 126 leave space at portions close to the back of printhead 102 for the flow of ink around the back surface thereof.

The ink supply unit is preferably formed from a multi-part plastic injection mould and the mould pieces eg. 110, 111 (FIG. 13) snap together around the sponge pieces 107, 109. Subsequently, a syringe type device can be inserted in the ink refill holes and the ink reservoirs filled with ink with the air flowing out of the air outlets 113-115. Subsequently, the adhesive tape portion 117 and plug 121 are attached and the printhead tested for operation capabilities. Subsequently, the ink supply cartridge 42 can be readily removed for refilling by means of removing the ink supply cartridge, performing a washing cycle, and then utilising the holes for the insertion of a refill syringe filled with ink for refilling the ink chamber before returning the ink supply cartridge 42 to a camera.

Turning now to FIG. 15, there is shown an example layout of the Image Capture and Processing Chip (ICP) 48.

The Image Capture and Processing Chip 48 provides most

of the electronic functionality of the camera with the exception of the print head chip. The chip 48 is a highly integrated system. It combines CMOS image sensing, analog to digital conversion, digital image processing, DRAM storage, ROM, and miscellaneous control functions in a single chip.

The chip is estimated to be around 32 mm² using a

leading edge 0.18 micron CMOS/DRAM/APS process. The chip size and cost can scale somewhat with Moore's law, but is dominated by a CMOS active pixel sensor array 201, so scaling is limited as the sensor pixels approach the diffraction limit.

The ICP 48 includes CMOS logic, a CMOS image sensor, DRAM, and analog circuitry. A very small amount of flash memory or other non-volatile memory is also preferably included for protection against reverse engineering.

Alternatively, the ICP can readily be divided into two chips: one for the CMOS imaging array, and the other for the remaining circuitry. The cost of this two chip solution should not be significantly different than the single chip ICP, as the extra cost of packaging and bond-pad area is somewhat cancelled by the reduced total wafer area requiring the color filter fabrication steps. The ICP preferably contains the following functions:

Function 1.5 megapixel image sensor Analog Signal Processors Image sensor column decoders Image sensor row decoders Function Analogue to Digital Conversion (ADC) Column ADC's Auto exposure 12 Mbits of DRAM DRAM Address Generator Color interpolator Convolver Color ALU Halftone matrix ROM Digital halftoning Print head interface 8 bit CPU core Program ROM Flash memory Scratchpad SRAM Parallel interface (8 bit) Motor drive transistors (5) Clock PLL JTAG test interface Test circuits Busses Bond pads

The CPU, DRAM, Image sensor, ROM, Flash memory, Parallel interface, JTAG interface and ADC can be vendor supplied cores. The ICP is intended to run on 1.5V to minimize power consumption and allow convenient operation from two AA type battery cells.

FIG. 15 illustrates a layout of the ICP 48. The ICP 48 is dominated by the imaging array 201, which consumes around 80% of the chip area. The imaging array is a CMOS 4 transistor active pixel design with a resolution of 1,500×1,000. The array can be divided into the conventional configuration, with two green pixels, one red pixel, and one blue pixel in each pixel group. There are 750×500 pixel groups in the imaging array.

The latest advances in the field of image sensing and CMOS image sensing in particular can be found in the October, 1997 issue of IEEE Transactions on Electron Devices and, in particular, pages 1689 to 1968. Further, a specific implementation similar to that disclosed in the present application is disclosed in Wong et. al, “CMOS Active Pixel Image Sensors Fabricated Using a 1.8V, 0.25 μm CMOS Technology”, IEDM 1996, page 915.

The imaging array uses a 4 transistor active pixel design of a standard configuration. To minimize chip area and therefore cost, the image sensor pixels should be as small as feasible with the technology available. With a four transistor cell, the typical pixel size scales as 20 times the lithographic feature size. This allows a minimum pixel area of around 3.6 μm×3.6 μm. However, the photosite must be substantially above the diffraction limit of the lens. It is also advantageous to have a square photosite, to maximize the margin over the diffraction limit in both horizontal and vertical directions. In this case, the photosite can be specified as 2.5 μm×2.5 μm. The photosite can be a photogate, pinned photodiode, charge modulation device, or other sensor.

The four transistors are packed as an ‘L’ shape, rather than a rectangular region, to allow both the pixel and the photosite to be square. This reduces the transistor packing density slightly, increasing pixel size. However, the advantage in avoiding the diffraction limit is greater than the small decrease in packing density.

The transistors also have a gate length which is longer than the minimum for the process technology. These have been increased from a drawn length of 0.18 micron to a drawn length of 0.36 micron. This is to improve the transistor matching by making the variations in gate length represent a smaller proportion of the total gate length.

The extra gate length, and the ‘L’ shaped packing, mean that the transistors use more area than the minimum for the technology. Normally, around 8 μm² would be required for rectangular packing. Preferably, 9.75 μm² has been allowed for the transistors.

The total area for each pixel is 16 μm², resulting from a pixel size of 4 μm×4 μm. With a resolution of 1,500×1,000, the area of the imaging array 101 is 6,000 μm×4,000 μm, or 24 mm².

The presence of a color image sensor on the chip affects the process required in two major ways:

The CMOS fabrication process should be optimized to minimize dark current

Color filters are required. These can be fabricated using dyed photosensitive polyimides, resulting in an added process complexity of three spin coatings, three photolithographic steps, three development steps, and three hardbakes.

There are 15,000 analog signal processors (ASPs) 205, one for each of the columns of the sensor. The ASPs amplify the signal, provide a dark current reference, sample and hold the signal, and suppress the fixed pattern noise (FPN).

There are 375 analog to digital converters 206, one for each four columns of the sensor array. These may be delta-sigma or successive approximation type ADC's. A row of low column ADC's are used to reduce the conversion speed required, and the amount of analog signal degradation incurred before the signal is converted to digital. This also eliminates the hot spot (affecting local dark current) and the substrate coupled noise that would occur if a single high speed ADC was used. Each ADC also has two four bit DAC's which trim the offset and scale of the ADC to further reduce FPN variations between columns. These DAC's are controlled by data stored in flash memory during chip testing.

The column select logic 204 is a 1:1500 decoder which enables the appropriate digital output of the ADCs onto the output bus. As each ADC is shared by four columns, the least significant two bits of the row select control 4 input analog multiplexors.

A row decoder 207 is a 1:1000 decoder which enables the appropriate row of the active pixel sensor array. This selects which of the 1000 rows of the imaging array is connected to analog signal processors. As the rows are always accessed in sequence, the row select logic can be implemented as a shift register.

An auto exposure system 208 adjusts the reference voltage of the ADC 205 in response to the maximum intensity sensed during the previous frame period. Data from the green pixels is passed through a digital peak detector. The peak value of the image frame period before capture (the reference frame) is provided to a digital to analogue converter (DAC), which generates the global reference voltage for the column ADCs. The peak detector is reset at the beginning of the reference frame. The minimum and maximum values of the three RGB color components are also collected for color correction.

The second largest section of the chip is consumed by a DRAM 210 used to hold the image. To store the 1,500×1,000 image from the sensor without compression, 1.5 Mbytes of DRAM 210 are required. This equals 12 Mbits, or slightly less than 5% of a 256 Mbit DRAM. The DRAM technology assumed is of the 256 Mbit generation implemented using 0.18 μm CMOS.

Using a standard 8F cell, the area taken by the memory array is 3.11 mm². When row decoders, column sensors, redundancy, and other factors are taken into account, the DRAM requires around 4 mm².

This DRAM 210 can be mostly eliminated if analog storage of the image signal can be accurately maintained in the CMOS imaging array for the two seconds required to print the photo. However, digital storage of the image is preferable as it is maintained without degradation, is insensitive to noise, and allows copies of the photo to be printed considerably later.

A DRAM address generator 211 provides the write and read addresses to the DRAM 210. Under normal operation, the write address is determined by the order of the data read from the CMOS image sensor 201. This will typically be a simple raster format. However, the data can be read from the sensor 201 in any order, if matching write addresses to the DRAM are generated. The read order from the DRAM 210 will normally simply match the requirements of a color interpolator and the print head. As the cyan, magenta, and yellow rows of the print head are necessarily offset by a few pixels to allow space for nozzle actuators, the colors are not read from the DRAM simultaneously. However, there is plenty of time to read all of the data from the DRAM many times during the printing process. This capability is used to eliminate the need for FIFOs in the print head interface, thereby saving chip area. All three RGB image components can be read from the DRAM each time color data is required. This allows a color space converter to provide a more sophisticated conversion than a simple linear RGB to CMY conversion.

Also, to allow two dimensional filtering of the image data without requiring line buffers, data is re-read from the DRAM array.

The address generator may also implement image effects in certain models of camera. For example, passport photos are generated by a manipulation of the read addresses to the DRAM. Also, image framing effects (where the central image is reduced), image warps, and kaleidoscopic effects can all be generated by manipulating the read addresses of the DRAM.

While the address generator 211 may be implemented with substantial complexity if effects are built into the standard chip, the chip area required for the address generator is small, as it consists only of address counters and a moderate amount of random logic.

A color interpolator 214 converts the interleaved pattern of red, 2×green, and blue pixels into RGB pixels. It consists of three 8 bit adders and associated registers. The divisions are by either 2 (for green) or 4 (for red and blue) so they can be implemented as fixed shifts in the output connections of the adders.

A convolver 215 is provided as a sharpening filter which applies a small convolution kernel (5×5) to the red, green, and blue planes of the image. The convolution kernel for the green plane is different from that of the red and blue planes, as green has twice as many samples. The sharpening filter has five functions:

To improve the color interpolation from the linear interpolation provided by the color interpolator, to a close approximation of a sinc interpolation.

To compensate for the image ‘softening’ which occurs during digitization.

To adjust the image sharpness to match average consumer preferences, which are typically for the image to be slightly sharper than reality. As the single use camera is intended as a consumer product, and not a professional photographic products, the processing can match the most popular settings, rather than the most accurate.

To suppress the sharpening of high frequency (individual pixel) noise. The function is similar to the ‘unsharp mask’ process.

To antialias Image Warping.

These functions are all combined into a single convolution matrix. As the pixel rate is low (less than 1 Mpixel per second) the total number of multiplies required for the three color channels is 56 million multiplies per second. This can be provided by a single multiplier. Fifty bytes of coefficient ROM are also required.

A color ALU 113 combines the functions of color compensation and color space conversion into the one matrix multiplication, which is applied to every pixel of the frame. As with sharpening, the color correction should match the most popular settings, rather than the most accurate.

A color compensation circuit of the color ALU provides compensation for the lighting of the photo. The vast majority of photographs are substantially improved by a simple color compensation, which independently normalizes the contrast and brightness of the three color components.

A color look-up table (CLUT) 212 is provided for each color component. These are three separate 256×8 SRAMs, requiring a total of 6,144 bits. The CLUTs are used as part of the color correction process. They are also used for color special effects, such as stochastically selected “wild color” effects.

A color space conversion system of the color ALU converts from the RGB color space of the image sensor to the CMY color space of the printer. The simplest conversion is a 1's complement of the RGB data. However, this simple conversion assumes perfect linearity of both color spaces, and perfect dye spectra for both the color filters of the image sensor, and the ink dyes. At the other extreme is a tri-linear interpolation of a sampled three dimensional arbitrary transform table. This can effectively match any non-linearity or differences in either color space. Such a system is usually necessary to obtain good color space conversion when the print engine is a color electrophotographic.

However, since the non-linearity of a halftoned ink jet output is very small, a simpler system can be used. A simple matrix multiply can provide excellent results. This requires nine multiplies and six additions per contone pixel. However, since the contone pixel rate is low (less than 1 Mpixel/sec) these operations can share a single multiplier and adder. The multiplier and adder are used in a color ALU which is shared with the color compensation function.

Digital halftoning can be performed as a dispersed dot ordered dither using a stochastic optimized dither cell. A halftone matrix ROM 216 is provided for storing dither cell coefficients. A dither cell size of 32×32 is adequate to ensure that the cell repeat cycle is not visible. The three colors—cyan, magenta, and yellow—are all dithered using the same cell, to ensure maximum co-positioning of the ink dots. This minimizes ‘muddying’ of the mid-tones which results from bleed of dyes from one dot to adjacent dots while still wet. The total ROM size required is 1 KByte, as the one ROM is shared by the halftoning units for each of the three colors.

The digital halftoning used is dispersed dot ordered dither with stochastic optimized dither matrix. While dithering does not produce an image quite as ‘sharp’ as error diffusion, it does produce a more accurate image with fewer artifacts. The image sharpening produced by error diffusion is artificial, and less controllable and accurate than ‘unsharp mask’ filtering performed in the contone domain. The high print resolution (1,600 dpi×1,600 dpi) results in excellent quality when using a well formed stochastic dither matrix.

Digital halftoning is performed by a digital halftoning unit 217 using a simple comparison between the contone information from the DRAM 210 and the contents of the dither matrix 216. During the halftone process, the resolution of the image is changed from the 250 dpi of the captured contone image to the 1,600 dpi of the printed image. Each contone pixel is converted to an average of 40.96 halftone dots.

The ICP incorporates a 16 bit microcontroller CPU core 219 to run the miscellaneous camera functions, such as reading the buttons, controlling the motor and solenoids, setting up the hardware, and authenticating the refill station. The processing power required by the CPU is very modest, and a wide variety of processor cores can be used. As the entire CPU program is run from a small ROM 220. Program compatibility between camera versions is not important, as no external programs are run. A 2 Mbit (256 Kbyte) program and data ROM 220 is included on chip. Most of this ROM space is allocated to data for outline graphics and fonts for specialty cameras. The program requirements are minor. The single most complex task is the encrypted authentication of the refill station. The ROM requires a single transistor per bit.

A Flash memory 221 may be used to store a 128 bit authentication code. This provides higher security than storage of the authentication code in ROM, as reverse engineering can be made essentially impossible. The Flash memory is completely covered by third level metal, making the data impossible to extract using scanning probe microscopes or electron beams. The authentication code is stored in the chip when manufactured. At least two other Flash bits are required for the authentication process: a bit which locks out reprogramming of the authentication code, and a bit which indicates that the camera has been refilled by an authenticated refill station. The flash memory can also be used to store FPN correction data for the imaging array. Additionally, a phase locked loop resealing parameter is stored for scaling the clocking cycle to an appropriate correct time. The clock frequency does not require crystal accuracy since no date functions are provided. To eliminate the cost of a crystal, an on chip oscillator with a phase locked loop 224 is used. As the frequency of an on-chip oscillator is highly variable from chip to chip, the frequency ratio of the oscillator to the PLL is digitally trimmed during initial testing. The value is stored in Flash memory 221. This allows the clock PLL to control the ink-jet heater pulse width with sufficient accuracy.

A scratchpad SRAM is a small static RAM 222 with a 6T cell. The scratchpad provided temporary memory for the 16 bit CPU. 1024 bytes is adequate.

A print head interface 223 formats the data correctly for the print head. The print head interface also provides all of the timing signals required by the print head. These timing signals may vary depending upon temperature, the number of dots printed simultaneously, the print medium in the print roll, and the dye density of the ink in the print roll.

The following is a table of external connections to the print head interface:

Connection Function Pins DataBits[0-7] Independent serial data to the eight segments  8 of the print head BitClock Main data clock for the print head  1 ColorEnable[0-2] Independent enable signals for the CMY  3 actuators, allowing different pulse times for each color. BankEnable[0-1] Allows either simultaneous or interleaved  2 actuation of two banks of nozzles. This allows two different print speed/power consumption tradeoffs NozzleSelect[0-4] Selects one of 32 banks of nozzles for  5 simultaneous actuation ParallelXferClock Loads the parallel transfer register with the  1 data from the shift registers Total 20

The print head utilized is composed of eight identical segments, each 1.25 cm long. There is no connection between the segments on the print head chip. Any connections required are made in the external TAB bonding film, which is double sided. The division into eight identical segments is to simplify lithography using wafer steppers. The segment width of 1.25 cm fits easily into a stepper field. As the print head chip is long and narrow (10 cm×0.3 mm), the stepper field contains a single segment of 32 print head chips. The stepper field is therefore 1.25 cm×1.6 cm. An average of four complete print heads are patterned in each wafer step.

A single BitClock output line connects to all 8 segments on the print head. The 8 DataBits lines lead one to each segment, and are clocked into the 8 segments on the print head simultaneously (on a BitClock pulse). For example, dot 0 is transferred to segment₀, dot 750 is transferred to segment₁, dot 1500 to segment₂ etc simultaneously.

The ParallelXferClock is connected to each of the 8 segments on the print head, so that on a single pulse, all segments transfer their bits at the same time.

The NozzleSelect, BankEnable and ColorEnable lines are connected to each of the 8 segments, allowing the print head interface to independently control the duration of the cyan, magenta, and yellow nozzle energizing pulses. Registers in the Print Head Interface allow the accurate specification of the pulse duration between 0 and 6 ms, with a typical duration of 2 ms to 3 ms.

A parallel interface 125 connects the ICP to individual static electrical signals. The CPU is able to control each of these connections as memory mapped I/O via a low speed bus.

The following is a table of connections to the parallel interface:

Connection Direction Pins Paper transport stepper motor Output 4 Capping solenoid Output 1 Copy LED Output 1 Photo button Input 1 Copy button Input 1 Total 8

Seven high current drive transistors eg. 227 are required. Four are for the four phases of the main stepper motor, two are for the guillotine motor, and the remaining transistor is to drive the capping solenoid. These transistors are allocated 20,000 square microns (600,000 F) each. As the transistors are driving highly inductive loads, they must either be turned off slowly, or be provided with a high level of back EMF protection. If adequate back EMF protection cannot be provided using the chip process chosen, then external discrete transistors should be used. The transistors are never driven at the same time as the image sensor is used. This is to avoid voltage fluctuations and hot spots affecting the image quality. Further, the transistors are located as far away from the sensor as possible.

A standard JTAG (Joint Test Action Group) interface 228 is included in the ICP for testing purposes and for interrogation by the refill station. Due to the complexity of the chip, a variety of testing techniques are required, including BIST (Built In Self Test) and functional block isolation. An overhead of 10% in chip area is assumed for chip testing circuitry for the random logic portions. The overhead for the large arrays the image sensor and the DRAM is smaller.

The JTAG interface is also used for authentication of the refill station. This is included to ensure that the cameras are only refilled with quality paper and ink at a properly constructed refill station, thus preventing inferior quality refills from occurring. The camera must authenticate the refill station, rather than vice versa. The secure protocol is communicated to the refill station during the automated test procedure. Contact is made to four gold plated spots on the ICP/print head TAB by the refill station as the new ink is injected into the print head.

FIG. 16 illustrates a rear view of the next step in the construction process whilst FIG. 17 illustrates a front view.

Turning now to FIG. 16, the assembly of the camera system proceeds via first assembling the ink supply mechanism 40. The flex PCB is interconnected with batteries 84, only one of which is shown, which are inserted in the middle portion of a print roll 85 which is wrapped around a plastic former 86. An end cap 89 is provided at the other end of the print roll 85 so as to fasten the print roll and batteries firmly to the ink supply mechanism.

The solenoid coil is interconnected (not shown) to interconnects 97, 98 (FIG. 8) which include leaf spring ends for interconnection with electrical contacts on the Flex PCB so as to provide for electrical control of the solenoid.

Turning now to FIGS. 17-19 the next step in the construction process is the insertion of the relevant gear trains into the side of the camera chassis. FIG. 17 illustrates a front view, FIG. 18 illustrates a rear view and FIG. 19 also illustrates a rear view. The first gear train, comprising gear wheels 22, 23 is utilised for driving the guillotine blade with the gear wheel 23 engaging the gear wheel 65 of FIG. 8. The second gear train, comprising gear wheels 24, 25 and 26 engage one end of the print roller 61 of FIG. 8. As best indicated in FIG. 18, the gear wheels mate with corresponding pins on the surface of the chassis with the gear wheel 26 being snap fitted into corresponding mating hole 27.

Next, as illustrated in FIG. 20, the assembled platten unit 60 is then inserted between the print roll 85 and aluminium cutting blade 43.

Turning now to FIG. 21, by way of illumination, there is illustrated the electrically interactive components of the camera system. As noted previously, the components are based around a Flex PCB board and include a TAB film 58 which interconnects the printhead 102 with the image sensor and processing chip 48. Power is supplied by two AA type batteries 83, 84 and a paper drive stepper motor 16 is provided in addition to a rotary guillotine motor 17.

An optical element 31 is provided for snapping into a top portion of the chassis 12. The optical element 31 includes portions defining an optical view finder 32, 33 which are slotted into mating portions 35, 36 in view finder channel 37. Also provided in the optical element 31 is a lensing system 38 for magnification of the prints left number in addition to an optical pipe element 39 for piping light from the LED 5 for external display.

Turning next to FIG. 22, the assembled unit 90 is then inserted into a front outer case 91 which includes button 4 for activation of printouts.

Turning now to FIG. 23, next, the unit 90 is provided with a snap-on back cover 93 which includes a slot 6 and copy print button 7. A wrapper label containing instructions and advertising (not shown) is then wrapped around the outer surface of the camera system and pinch clamped to the cover by means of clamp strip 96 which can comprise a flexible plastic or rubber strip.

Subsequently, the preferred embodiment is ready for use as a one time use camera system that provides for instant output images on demand. It will be evident that the preferred embodiment further provides for a refillable camera system. A used camera can be collected and its outer plastic cases removed and recycled. A new paper roll and batteries can be added and the ink cartridge refilled. A series of automatic test routines can then be carried out to ensure that the printer is properly operational. Further, in order to ensure only authorised refills are conducted so as to enhance quality, routines in the on-chip program ROM can be executed such that the camera authenticates the refilling station using a secure protocol. Upon authentication, the camera can reset an internal paper count and an external case can be fitted on the camera system with a new outer label. Subsequent packing and shipping can then take place.

It will be further readily evident to those skilled in the art that the program ROM can be modified so as to allow for a variety of digital processing routines. In addition to the digitally enhanced photographs optimised for mainstream consumer preferences, various other models can readily be provided through mere re-programming of the program ROM. For example, a sepia classic old fashion style output can be provided through a remapping of the colour mapping function. A further alternative is to provide for black and white outputs again through a suitable colour remapping algorithm. Minimum colour can also be provided to add a touch of colour to black and white prints to produce the effect that was traditionally used to colourize black and white photos. Further, passport photo output can be provided through suitable address remappings within the address generators. Further, edge filters can be utilised as is known in the field of image processing to produce sketched art styles. Further, classic wedding borders and designs can be placed around an output image in addition to the provision of relevant clip arts. For example, a wedding style camera might be provided. Further, a panoramic mode can be provided so as to output the well known panoramic format of images. Further, a postcard style output can be provided through the printing of postcards including postage on the back of a print roll surface. Further, cliparts can be provided for special events such as Halloween, Christmas etc. Further, kaleidoscopic effects can be provided through address remappings and wild colour effects can be provided through remapping of the colour lookup table. Many other forms of special event cameras can be provided for example, cameras dedicated to the Olympics, movie tie-ins, advertising and other special events.

The operational mode of the camera can be programmed so that upon the depressing of the take photo a first image is sampled by the sensor array to determine irrelevant parameters. Next a second image is again captured which is utilised for the output. The captured image is then manipulated in accordance with any special requirements before being initially output on the paper roll. The LED light is then activated for a predetermined time during which the DRAM is refreshed so as to retain the image. If the print copy button is depressed during this predetermined time interval, a further copy of the photo is output. After the predetermined time interval where no use of the camera has occurred, the onboard CPU shuts down all power to the camera system until such time as the take button is again activated. In this way, substantial power savings can be realized.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per printhead, but is a major impediment to the fabrication of pagewidth print heads printheads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table under the heading Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems.

For ease of manufacture using standard process equipment, the printhead is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the printhead is 100 mm long, with a width which depends upon the ink jet type. The smallest printhead designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The printheads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the printhead by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The printhead is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

The present invention is useful in the field of digital printing, in particular, ink jet printing.

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. These are designated IJ01 to IJ45 above which matches the docket numbers in the table under the heading Cross References to Related Applications.

Other ink jet configurations can readily be derived from these 45 forty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into ink jet printheads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a print technology may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Thermal An electrothermal ♦ Large force ♦ High power ♦ Canon Bubblejet bubble heater heats the ink to generated ♦ Ink carrier 1979 Endo et al GB above boiling point, ♦ Simple limited to water patent 2,007,162 transferring significant construction ♦ Low efficiency ♦ Xerox heater-in- heat to the aqueous ♦ No moving parts ♦ High pit 1990 Hawkins et ink. A bubble ♦ Fast operation temperatures al U.S. Pat. No. 4,899,181 nucleates and quickly ♦ Small chip area required ♦ Hewlett-Packard forms, expelling the required for actuator ♦ High mechanical TIJ 1982 Vaught et ink. stress al U.S. Pat. No. 4,490,728 The efficiency of the ♦ Unusual process is low, with materials required typically less than ♦ Large drive 0.05% of the electrical transistors energy being ♦ Cavitation causes transformed into actuator failure kinetic energy of the ♦ Kogation reduces drop. bubble formation ♦ Large print heads are difficult to fabricate Piezo- A piezoelectric crystal ♦ Low power ♦ Very large area ♦ Kyser et al U.S. Pat. No. electric such as lead consumption required for actuator 3,946,398 lanthanum zirconate ♦ Many ink types ♦ Difficult to ♦ Zoltan U.S. Pat. No. (PZT) is electrically can be used integrate with 3,683,212 activated, and either ♦ Fast operation electronics ♦ 1973 Stemme expands, shears, or ♦ High efficiency ♦ High voltage U.S. Pat. No. 3,747,120 bends to apply drive transistors ♦ Epson Stylus pressure to the ink, required ♦ Tektronix ejecting drops. ♦ Full pagewidth ♦ IJ04 print heads impractical due to actuator size ♦ Requires electrical poling in high field strengths during manufacture Electro- An electric field is ♦ Low power ♦ Low maximum ♦ Seiko Epson, strictive used to activate consumption strain (approx. Usui et all JP electrostriction in ♦ Many ink types 0.01%) 253401/96 relaxor materials such can be used ♦ Large area ♦ IJ04 as lead lanthanum ♦ Low thermal required for actuator zirconate titanate expansion due to low strain (PLZT) or lead ♦ Electric field ♦ Response speed magnesium niobate strength required is marginal (˜10 (PMN). (approx. 3.5 V/μm) μs) can be generated ♦ High voltage without difficulty drive transistors ♦ Does not require required electrical poling ♦ Full pagewidth print heads impractical due to actuator size Ferro- An electric field is ♦ Low power ♦ Difficult to ♦ IJ04 electric used to induce a phase consumption integrate with transition between the ♦ Many ink types electronics antiferroelectric (AFE) can be used ♦ Unusual and ferroelectric (FE) ♦ Fast operation materials such as phase. Perovskite (<1 μs) PLZSnT are materials such as tin ♦ Relatively high required modified lead longitudinal strain ♦ Actuators require lanthanum zirconate ♦ High efficiency a large area titanate (PLZSnT) ♦ Electric field exhibit large strains of strength of around 3 up to 1% associated V/μm can be readily with the AFE to FE provided phase transition. Electro- Conductive plates are ♦ Low power ♦ Difficult to ♦ IJ02, IJ04 static plates separated by a consumption operate electrostatic compressible or fluid ♦ Many ink types devices in an dielectric (usually air). can be used aqueous Upon application of a ♦ Fast operation environment voltage, the plates ♦ The electrostatic attract each other and actuator will displace ink, causing normally need to be drop ejection. The separated from the conductive plates may ink be in a comb or ♦ Very large area honeycomb structure, required to achieve or stacked to increase high forces the surface area and ♦ High voltage therefore the force. drive transistors may be required ♦ Full pagewidth print heads are not competitive due to actuator size Electro- A strong electric field ♦ Low current ♦ High voltage ♦ 1989 Saito et al, static pull is applied to the ink, consumption required U.S. Pat. No. 4,799,068 on ink whereupon ♦ Low temperature ♦ May be damaged ♦ 1989 Miura et al, electrostatic attraction by sparks due to air U.S. Pat. No. 4,810,954 accelerates the ink breakdown ♦ Tone-jet towards the print ♦ Required field medium. strength increases as the drop size decreases ♦ High voltage drive transistors required ♦ Electrostatic field attracts dust Permanent An electromagnet ♦ Low power ♦ Complex ♦ IJ07, IJ10 magnet directly attracts a consumption fabrication electro- permanent magnet, ♦ Many ink types ♦ Permanent magnetic displacing ink and can be used magnetic material causing drop ejection. ♦ Fast operation such as Neodymium Rare earth magnets ♦ High efficiency Iron Boron (NdFeB) with a field strength ♦ Easy extension required. around 1 Tesla can be from single nozzles ♦ High local used. Examples are: to pagewidth print currents required Samarium Cobalt heads ♦ Copper (SaCo) and magnetic metalization should materials in the be used for long neodymium iron boron electromigration family (NdFeB, lifetime and low NdDyFeBNb, resistivity NdDyFeB, etc) ♦ Pigmented inks are usually infeasible ♦ Operating temperature limited to the Curie temperature (around 540K) Soft A solenoid induced a ♦ Low power ♦ Complex ♦ IJ01, IJ05, IJ08, magnetic magnetic field in a soft consumption fabrication IJ10, IJ12, IJ14, core electro- magnetic core or yoke ♦ Many ink types ♦ Materials not IJ15, IJ17 magnetic fabricated from a can be used usually present in a ferrous material such ♦ Fast operation CMOS fab such as as electroplated iron ♦ High efficiency NiFe, CoNiFe, or alloys such as CoNiFe ♦ Easy extension CoFe are required [1], CoFe, or NiFe from single nozzles ♦ High local alloys. Typically, the to pagewidth print currents required soft magnetic material heads ♦ Copper is in two parts, which ♦ metalization should are normally held be used for long apart by a spring. electromigration When the solenoid is lifetime and low actuated, the two parts resistivity attract, displacing the ♦ Electroplating is ink. required ♦ High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Lorenz The Lorenz force ♦ Low power ♦ Force acts as a ♦ IJ06, IJ11, IJ13, force acting on a current consumption twisting motion IJ16 carrying wire in a ♦ Many ink types ♦ Typically, only a magnetic field is can be used quarter of the utilized. ♦ Fast operation solenoid length This allows the ♦ High efficiency provides force in a magnetic field to be ♦ Easy extension useful direction supplied externally to from single nozzles ♦ High local the print head, for to pagewidth print currents required example with rare heads ♦ Copper earth permanent metalization should magnets. be used for long Only the current electromigration carrying wire need be lifetime and low fabricated on the print- resistivity head, simplifying ♦ Pigmented inks materials are usually requirements. infeasible Magneto- The actuator uses the ♦ Many ink types ♦ Force acts as a ♦ Fischenbeck, striction giant magnetostrictive can be used twisting motion U.S. Pat. No. 4,032,929 effect of materials ♦ Fast operation ♦ Unusual ♦ IJ25 such as Terfenol-D (an ♦ Easy extension materials such as alloy of terbium, from single nozzles Terfenol-D are dysprosium and iron to pagewidth print required developed at the Naval heads ♦ High local Ordnance Laboratory, ♦ High force is currents required hence Ter-Fe-NOL). available ♦ Copper For best efficiency, the metalization should actuator should be pre- be used for long stressed to approx. 8 electromigration MPa. lifetime and low resistivity ♦ Pre-stressing may be required Surface Ink under positive ♦ Low power ♦ Requires ♦ Silverbrook, EP tension pressure is held in a consumption supplementary force 0771 658 A2 and reduction nozzle by surface ♦ Simple to effect drop related patent tension. The surface construction separation applications tension of the ink is ♦ No unusual ♦ Requires special reduced below the materials required in ink surfactants bubble threshold, fabrication ♦ Speed may be causing the ink to ♦ High efficiency limited by surfactant egress from the ♦ Easy extension properties nozzle. from single nozzles to pagewidth print heads Viscosity The ink viscosity is ♦ Simple ♦ Requires ♦ Silverbrook, EP reduction locally reduced to construction supplementary force 0771 658 A2 and select which drops are ♦ No unusual to effect drop related patent to be ejected. A materials required in separation applications viscosity reduction can fabrication ♦ Requires special be achieved ♦ Easy extension ink viscosity electrothermally with from single nozzles properties most inks, but special to pagewidth print ♦ High speed is inks can be engineered heads difficult to achieve for a 100:1 viscosity ♦ Requires reduction. oscillating ink pressure ♦ A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is ♦ Can operate ♦ Complex drive ♦ 1993 Hadimioglu generated and without a nozzle circuitry et al, EUP 550,192 focussed upon the plate ♦ Complex ♦ 1993 Elrod et al, drop ejection region. fabrication EUP 572,220 ♦ Low efficiency ♦ Poor control of drop position ♦ Poor control of drop volume Thermo- An actuator which ♦ Low power ♦ Efficient aqueous ♦ IJ03, IJ09, IJ17, elastic bend relies upon differential consumption operation requires a IJ18, IJ19, IJ20, actuator thermal expansion ♦ Many ink types thermal insulator on IJ21, IJ22, IJ23, upon Joule heating is can be used the hot side IJ24, IJ27, IJ28, used. ♦ Simple planar ♦ Corrosion IJ29, IJ30, IJ31, fabrication prevention can be IJ32, IJ33, IJ34, ♦ Small chip area difficult IJ35, IJ36, IJ37, required for each ♦ Pigmented inks IJ38, IJ39, IJ40, actuator may be infeasible, IJ41 ♦ Fast operation as pigment particles ♦ High efficiency may jam the bend ♦ CMOS actuator compatible voltages and currents ♦ Standard MEMS processes can be used ♦ Easy extension from single nozzles to pagewidth print heads High CTE A material with a very ♦ High force can ♦ Requires special ♦ IJ09, IJ17, IJ18, thermo- high coefficient of be generated material (e.g. PTFE) IJ20, IJ21, IJ22, elastic thermal expansion ♦ Three methods of ♦ Requires a PTFE IJ23, IJ24, IJ27, actuator (CTE) such as PTFE deposition are deposition process, IJ28, IJ29, IJ30, polytetrafluoroethylene under development: which is not yet IJ31, IJ42, IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44 high CTE materials deposition (CVD), fabs are usually non- spin coating, and ♦ PTFE deposition conductive, a heater evaporation cannot be followed fabricated from a ♦ PTFE is a with high conductive material is candidate for low temperature (above incorporated. A 50 μm dielectric constant 350° C.) processing long PTFE bend insulation in ULSI ♦ Pigmented inks actuator with ♦ Very low power may be infeasible, polysilicon heater and consumption as pigment particles 15 mW power input ♦ Many ink types may jam the bend can provide 180 μN can be used actuator force and 10 μm ♦ Simple planar deflection. Actuator fabrication motions include: ♦ Small chip area Bend required for each Push actuator Buckle ♦ Fast operation Rotate ♦ High efficiency ♦ CMOS compatible voltages and currents ♦ Easy extension from single nozzles to pagewidth print heads Conductive A polymer with a high ♦ High force can ♦ Requires special ♦ IJ24 polymer coefficient of thermal be generated materials thermo- expansion (such as ♦ Very low power development (High elastic PTFE) is doped with consumption CTE conductive actuator conducting substances ♦ Many ink types polymer) to increase its can be used ♦ Requires a PTFE conductivity to about 3 ♦ Simple planar deposition process, orders of magnitude fabrication which is not yet below that of copper. ♦ Small chip area standard in ULSI The conducting required for each fabs polymer expands actuator ♦ PTFE deposition when resistively ♦ Fast operation cannot be followed heated. ♦ High efficiency with high Examples of ♦ CMOS temperature (above conducting dopants compatible voltages 350° C.) processing include: and currents ♦ Evaporation and Carbon nanotubes ♦ Easy extension CVD deposition Metal fibers from single nozzles techniques cannot Conductive polymers to pagewidth print be used such as doped heads ♦ Pigmented inks polythiophene may be infeasible, Carbon granules as pigment particles may jam the bend actuator Shape A shape memory alloy ♦ High force is ♦ Fatigue limits ♦ IJ26 memory such as TiNi (also available (stresses maximum number alloy known as Nitinol — of hundreds of MPa) of cycles Nickel Titanium alloy ♦ Large strain is ♦ Low strain (1%) developed at the Naval available (more than is required to extend Ordnance Laboratory) 3%) fatigue resistance is thermally switched ♦ High corrosion ♦ Cycle rate between its weak resistance limited by heat martensitic state and ♦ Simple removal its high stiffness construction ♦ Requires unusual austenic state. The ♦ Easy extension materials (TiNi) shape of the actuator from single nozzles ♦ The latent heat of in its martensitic state to pagewidth print transformation must is deformed relative to heads be provided the austenic shape. ♦ Low voltage ♦ High current The shape change operation operation causes ejection of a ♦ Requires pre- drop. stressing to distort the martensitic state Linear Linear magnetic ♦ Linear Magnetic ♦ Requires unusual ♦ IJ12 Magnetic actuators include the actuators can be semiconductor Actuator Linear Induction constructed with materials such as Actuator (LIA), Linear high thrust, long soft magnetic alloys Permanent Magnet travel, and high (e.g. CoNiFe) Synchronous Actuator efficiency using ♦ Some varieties (LPMSA), Linear planar also require Reluctance semiconductor permanent magnetic Synchronous Actuator fabrication materials such as (LRSA), Linear techniques Neodymium iron Switched Reluctance ♦ Long actuator boron (NdFeB) Actuator (LSRA), and travel is available ♦ Requires the Linear Stepper ♦ Medium force is complex multi- Actuator (LSA). available phase drive circuitry ♦ Low voltage ♦ High current operation operation

BASIC OPERATION MODE Description Advantages Disadvantages Examples Actuator This is the simplest * Simple operation * Drop repetition * Thermal ink jet directly mode of operation: the * No external rate is usually * Piezoelectric ink pushes ink actuator directly fields required limited to around 10 jet supplies sufficient * Satellite drops kHz. However, this * IJ01, IJ02, IJ03, kinetic energy to expel can be avoided if is not fundamental IJ04, IJ05, IJ06, the drop. The drop drop velocity is less to the method, but is IJ07, IJ09, IJ11, must have a sufficient than 4 m/s related to the refill IJ12, IJ14, IJ16, velocity to overcome * Can be efficient, method normally IJ20, IJ22, IJ23, the surface tension. depending upon the used IJ24, IJ25, IJ26, actuator used * All of the drop IJ27, IJ28, IJ29, kinetic energy must IJ30, IJ31, IJ32, be provided by the IJ33, IJ34, IJ35, actuator IJ36, IJ37, IJ38, * Satellite drops IJ39, IJ40, IJ41, usually form if drop IJ42, IJ43, IJ44 velocity is greater than 4.5 m/s Proximity The drops to be * Very simple print * Requires close * Silverbrook, EP printed are selected by head fabrication can proximity between 0771 658 A2 and some manner (e.g. be used the print head and related patent thermally induced * The drop the print media or applications surface tension selection means transfer roller reduction of does not need to * May require two pressurized ink). provide the energy print heads printing Selected drops are required to separate alternate rows of the separated from the ink the drop from the image in the nozzle by nozzle * Monolithic color contact with the print print heads are medium or a transfer difficult roller. Electro- The drops to be * Very simple print * Requires very * Silverbrook, EP static pull printed are selected by head fabrication can high electrostatic 0771 658 A2 and on ink some manner (e.g. be used field related patent thermally induced * The drop * Electrostatic field applications surface tension selection means for small nozzle * Tone-Jet reduction of does not need to sizes is above air pressurized ink). provide the energy breakdown Selected drops are required to separate * Electrostatic field separated from the ink the drop from the may attract dust in the nozzle by a nozzle strong electric fleld. Magnetic The drops to be * Very simple print * Requires * Silverbrook, EP pull on ink printed are selected by head fabrication can magnetic ink 0771 658 A2 and some manner (e.g. be used * Ink colors other related patent thermally induced * The drop than black are applications surface tension selection means difficult reduction of does not need to * Requires very pressurized ink). provide the energy high magnetic fields Selected drops are required to separate separated from the ink the drop from the in the nozzle by a nozzle strong magnetic field acting on the magnetic ink. Shutter The actuator moves a * High speed (>50 * Moving parts are * IJ13, IJ17, IJ21 shutter to block ink kHz) operation can required flow to the nozzle. The be achieved due to * Requires ink ink pressure is pulsed reduced refill time pressure modulator at a multiple of the * Drop timing can * Friction and wear drop ejection be very accurate must be considered frequency. * The actuator * Stiction is energy can be very possible low Shuttered The actuator moves a * Actuators with * Moving parts are * IJ08, IJ15, IJ18, grill shutter to block ink small travel can be required IJ19 flow through a grill to used * Requires ink the nozzle. The shutter * Actuators with pressure modulator movement need only small force can be * Friction and wear be equal to the width used must be considered of the grill holes. * High speed (>50 * Stiction is kHz) operation can possible be achieved Pulsed A pulsed magnetic * Extremely low * Requires an * IJ10 magnetic field attracts an ‘ink energy operation is external pulsed pull on ink pusher’ at the drop possible magnetic field pusher ejection frequency. An * No heat * Requires special actuator controls a dissipation materials for both catch, which prevents problems the actuator and the the ink pusher from ink pusher moving when a drop is * Complex not to be ejected. construction

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages Disadvantages Examples None The actuator directly * Simplicity of * Drop ejection * Most ink jets, fires the ink drop, and construction energy must be including there is no external * Simplicity of supplied by piezoelectric and field or other operation individual nozzle thermal bubble. mechanism required. * Small physical actuator * IJ01, IJ02, IJ03, size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24, IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The ink pressure * Oscillating ink * Requires external * Silverbrook, EP ink pressure oscillates, providing pressure can provide ink pressure 0771 658 A2 and (including much of the drop a refill pulse, * oscillator related patent acoustic ejection energy. The allowing higher * Ink pressure applications stimul- actuator selects which operating speed phase and amplitude * IJ08, IJ13, IJ15, ation) drops are to be fired * The actuators must be carefully IJ17, IJ18, IJ19, by selectively may operate with controlled IJ21 blocking or enabling much lower energy * Acoustic nozzles. The ink * Acoustic lenses reflections in the ink pressure oscillation can be used to focus chamber must be may be achieved by the sound on the designed for vibrating the print nozzles head, or preferably by an actuator in the ink supply. Media The print head is * Low power * Precision * Silverbrook, EP proximity placed in close * High accuracy assembly required 0771 658 A2 and proximity to the print * Simple print head * Paper fibers may related patent medium. Selected construction cause problems applications drops protrude from * Cannot print on the print head further rough substrates than unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer Drops are printed to a * High accuracy * Bulky * Silverbrook, EP roller transfer roller instead * Wide range of * Expensive 0771 658 A2 and of straight to the print print substrates can * Complex related patent medium. A transfer be used construction applications roller can also be used * Ink can be dried * Tektronix hot for proximity drop on the transfer roller melt piezoelectric separation. ink jet * Any of the IJ series Electro- An electric field is * Low power * Field strength * Silverbrook, EP static used to accelerate * Simple print head required for 0771 658 A2 and selected drops towards construction separation of small related patent the print medium. drops is near or applications above air * Tone-Jet breakdown Direct A magnetic field is * Low power * Requires * Silverbrook, EP magnetic used to accelerate * Simple print head magnetic ink 0771 658 A2 and field selected drops of construction * Requires strong related patent magnetic ink towards magnetic field applications the print medium. Cross The print head is * Does not require * Requires external * IJ06, IJ16 magnetic placed in a constant magnetic materials magnet field magnetic field. The to be integrated in * Current densities Lorenz force in a the print head may be high, current carrying wire manufacturing resulting in is used to move the process electromigration actuator. problems Pulsed A pulsed magnetic * Very low power * Complex print * IJ10 magnetic field is used to operation is possible head construction field cyclically attract a * Small print head * Magnetic paddle, which pushes size materials required in on the ink. A small print head actuator moves a catch, which selectively prevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples None No actuator * Operational * Many actuator * Thermal Bubble mechanical simplicity mechanisms have Ink jet amplification is used. insufficient travel, * IJ01, IJ02, IJ06, The actuator directly or insufficient force, IJ07, IJ16, IJ25, drives the drop to efficiently drive IJ26 ejection process. the drop ejection process Differential An actuator material * Provides greater * High stresses are * Piezoelectric expansion expands more on one travel in a reduced involved * IJ03, IJ09, IJ17, bend side than on the other. print head area * Care must be IJ18, IJ19, IJ20, actuator The expansion may be taken that the IJ21, IJ22, IJ23, thermal, piezoelectric, materials do not IJ24, IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32, other mechanism. The * Residual bend IJ33, IJ34, IJ35, bend actuator converts resulting from high IJ36, IJ37, IJ38, a high force low travel temperature or high IJ39, IJ42, IJ43, actuator mechanism to stress during IJ44 high travel, lower formation force mechanism. Transient A trilayer bend * Very good * High stresses are * IJ40, IJ41 bend actuator where the two temperature stability involved actuator outside layers are * High speed, as a * Care must be identical. This cancels new drop can be taken that the bend due to ambient fired before heat materials do not temperature and dissipates delaminate residual stress. The * Cancels residual actuator only responds stress of formation to transient heating of one side or the other. Reverse The actuator loads a * Better coupling * Fabrication * IJ05, IJ11 spring spring. When the to the ink complexity actuator is turned off, * High stress in the the spring releases. spring This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator A series of thin * Increased travel * Increased * Some stack actuators are stacked. * Reduced drive fabrication piezoelectric ink jets This can be voltage complexity * IJ04 appropriate where * Increased actuators require high possibility of short electric field strength, circuits due to such as electrostatic pinholes and piezoelectric actuators. Multiple Multiple smaller * Increases the * Actuator forces * IJ12, IJ13, IJ18, actuators actuators are used force available from may not add IJ20, IJ22, IJ28, simultaneously to an actuator linearly, reducing IJ42, IJ43 move the ink. Each * Multiple efficiency actuator need provide actuators can be only a portion of the positioned to control force required. ink flow accurately Linear A linear spring is used * Matches low * Requires print * IJ15 Spring to transform a motion travel actuator with head area for the with small travel and higher travel spring high force into a requirements longer travel, lower * Non-contact force motion. method of motion transformation Coiled A bend actuator is * Increases travel * Generally * IJ17, IJ21, IJ34, actuator coiled to provide * Reduces chip restricted to planar IJ35 greater travel in a area implementations reduced chip area. * Planar due to extreme implementations are fabrication difficulty relatively easy to in other orientations. fabricate. Flexure A bend actuator has a * Simple means of * Care must be * IJ10, IJ19, IJ33 bend small region near the increasing travel of taken not to exceed actuator fixture point, which a bend actuator the elastic limit in flexes much more the flexure area readily than the * Stress remainder of the distribution is very actuator. The actuator uneven flexing is effectively * Difficult to converted from an accurately model even coiling to an with finite element angular bend, resulting analysis in greater travel of the actuator tip. Catch The actuator controls a * Very low * Complex * IJ10 small catch. The catch actuator energy construction either enables or * Very small * Requires external disables movement of actuator size force an ink pusher that is * Unsuitable for controlled in a bulk pigmented inks manner. Gears Gears can be used to * Low force, low * Moving parts are * IJ13 increase travel at the travel actuators can required expense of duration. be used * Several actuator Circular gears, rack * Can be fabricated cycles are required and pinion, ratchets, using standard * More complex and other gearing surface MEMS drive electronics methods can be used. processes * Complex construction * Friction, friction, and wear are possible Buckle plate A buckle plate can be * Very fast * Must stay within * S. Hirata et al, used to change a slow movement elastic limits of the “An Ink-jet Head actuator into a fast achievable materials for long Using Diaphragm motion. It can also device life Microactuator”, convert a high force, * High stresses Proc. IEEE MEMS, low travel actuator involved Feb. 1996, pp 418- into a high travel, * Generally high 423. medium force motion. power requirement * IJ18, IJ27 Tapered A tapered magnetic * Linearizes the * Complex * IJ14 niagnetic pole can increase magnetic construction pole travel at the expense force/distance curve of force. Lever A lever and fulcrum is * Matches low * High stress * IJ32, IJ36, IJ37 used to transform a travel actuator with around the fulcrum motion with small higher travel travel and high force requirements into a motion with * Fulcrum area has longer travel and no linear movement, lower force. The lever and can be used for can also reverse the a fluid seal direction of travel. Rotary The actuator is * High mechanical * Complex * IJ28 impeller connected to a rotary advantage construction impeller. A small * The ratio of force * Unsuitable for angular deflection of to travel of the pigmented inks the actuator results in actuator can be a rotation of the matched to the impeller vanes, which nozzle requirements push the ink against by varying the stationary vanes and number of impeller out of the nozzle. vanes Acoustic A refractive or * No moving parts * Large area * 1993 Hadimioglu lens diffractive (e.g. zone required et al, EUP 550,192 plate) acoustic lens is * Only relevant for * 1993 Elrod et al, used to concentrate acoustic ink jets EUP 572,220 sound waves. Sharp A sharp point is used * Simple * Difficult to * Tone-jet conductive to concentrate an construction fabricate using point electrostatic field. standard VLSI processes for a surface ejecting ink- jet * Only relevant for electrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume The volume of the * Simple * High energy is * Hewlett-Packard expansion actuator changes, construction in the typically required to Thermal Ink jet pushing the ink in all case of thermal ink achieve volume * Canon Bubblejet directions. jet expansion. This leads to thermal stress, cavitation, and kogation in thermal ink jet implementations Linear, The actuator moves in * Efficient * High fabrication * IJ01, IJ02, IJ04, normal to a direction normal to coupling to ink complexity may be IJ07, IJ11, IJ14 chip surface the print head surface. drops ejected required to achieve The nozzle is typically normal to the perpendicuiar in the line of surface motion movement. Parallel to The actuator moves * Suitable for * Fabrication * IJ12, IJ13, IJ15, chip surface parallel to the print planar fabrication complexity IJ33,, IJ34, IJ35, head surface. Drop * Friction IJ36 ejection may still be * Stiction normal to the surface. Membrane An actuator with a * The effective * Fabrication * 1982 Howkins push high force but small area of the actuator complexity U.S. Pat. No. 4,459,601 area is used to push a becomes the * Actuator size stiff membrane that is membrane area * Difficulty of in contact with the ink. integration in a VLSI process Rotary The actuator causes * Rotary levers * Device * IJ05, IJ08, IJ13, the rotation of some may be used to complexity IJ28 element, such a grill or increase travel * May have impeller * Small chip area friction at a pivot requirements point Bend The actuator bends * A very small * Requires the * 1970 Kyser et al when energized. This change in actuator to be made U.S. Pat. No. 3,946,398 may be due to dimensions can be from at least two * 1973 Stemme differential thermal converted to a large distinct layers, or to U.S. Pat. No. 3,747,120 expansion, motion. have a thermal * IJ03, IJ09, IJI0, piezoelectric difference across the IJ19, IJ23, IJ24, expansion, actuator IJ25, IJ29, IJ30, magnetostriction, or IJ31, IJ33, IJ34, other form of relative IJ35 dimensional change. Swivel The actuator swivels * Allows operation * Inefficient * IJ06 around a central pivot. where the net linear coupling to the ink This motion is suitable force on the paddle motion where there are is zero opposite forces * Small chip area applied to opposite requirements sides of the paddle, e.g. Lorenz force. Straighten The actuator is * Can be used with * Requires careful * IJ26, IJ32 normally bent, and shape memory balance of stresses straightens when alloys where the to ensure that the energized. austenic phase is quiescent bend is planar accurate Double The actuator bends in * One actuator can * Difficult to make * IJ36, IJ37, IJ38 bend one direction when be used to power the drops ejected by one element is two nozzles. both bend directions energized, and bends * Reduced chip identical. the other way when size. * A small another element is * Not sensitive to efficiency loss energized. ambient temperature compared to equivalent single bend actuators. Shear Energizing the * Can increase the * Not readily * 1985 Fishbeck actuator causes a shear effective travel of applicable to other U.S. Pat. No. 4,584,590 motion in the actuator piezoelectric actuator material. actuators mechanisms Radial con- The actuator squeezes * Relatively easy * High force * 1970 Zoltan U.S. Pat. striction an ink reservoir, to fabricate single required No. 3,683,212 forcing ink from a nozzles from glass * Inefficient constricted nozzle. tubing as * Difficult to macroscopic integrate with VLSI structures processes Coil/uncoil A coiled actuator * Easy to fabricate * Difficult to * IJ17, IJ21, IJ34, uncoils or coils more as a planar VLSI fabricate for non- IJ35 tightly. The motion of process planar devices the free end of the * Small area * Poor out-of-plane actuator ejects the ink. required, therefore stiffness low cost Bow The actuator bows (or * Can increase the * Maximum travel * IJ16, IJ18, IJ27 buckles) in the middle speed of travel is constrained when energized. * Mechanically * High force rigid required Push-Pull Two actuators control * The structure is * Not readily * IJ18 a shutter. One actuator pinned at both ends, suitable for ink jets pulls the shutter, and so has a high out-of- which directly push the other pushes it. plane rigidity the ink Curl A set of actuators curl * Good fluid flow * Design * IJ20, IJ42 inwards inwards to reduce the to the region behind complexity volume of ink that the actuator they enclose. increases efficiency Curl A Set of actuators curl * Relatively simple * Relatively large * IJ43 outwards outwards, pressurizing construction chip area ink in a chamber surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes enclose * High efficiency * High fabrication * IJ22 a volume of ink. These * Small chip area complexity simultaneously rotate, * Not suitable for reducing the volume pigmented inks between the vanes. Acoustic The actuator vibrates * The actuator can * Large area * 1993 Hadimioglu vibration at a high frequency. be physically distant required for et al, EUP 550,192 from the ink efficient operation * 1993 Elrod et al, at useful frequencies EUP 572,220 * Acoustic coupling and crosstalk * Complex drive circuitry * Poor control of drop volume and position None In various ink jet * No moving parts * Various other * Silverbrook, EP designs the actuator tradeoffs are 0771 658 A2 and does not move. required to related patent eliminate moving applications parts * Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages Examples Surface This is the normal way * Fabrication * Low speed * Thermal ink jet tension that ink jets are simplicity * Surface tension * Piezoelectric ink refilled. After the * Operational force relatively jet actuator is energized, simplicity small compared to * IJ01-IJ07, IJ10- it typically returns actuator force IJ14, IJ16, IJ20, rapidly to its normal * Long refill time IJ22-IJ45 position. This rapid usually dominates return sucks in air the total repetition through the nozzle rate opening. The ink surface tension at the nozzle then exerts a small force restoring the meniscus to a minimum area. This force refills the nozzle. Shuttered Ink to the nozzle * High speed * Requires * IJ08, IJ13, IJ15, oscillating chamber is provided at * Low actuator common ink IJ17, IJ18, IJ19, ink pressure a pressure that energy, as the pressure oscillator IJ21 oscillates at twice the actuator need only * May not be drop ejection open or close the suitable for frequency. When a shutter, instead of pigmented inks drop is to be ejected, ejecting the ink drop the shutter is opened for 3 half cycles: drop ejection, actuator return, and refill. The shutter is then closed to prevent the nozzle chamber emptying during the next negative pressure cycle. Refill After the main * High speed, as * Requires two * IJ09 actuator actuator has ejected a the nozzle is independent drop a second (refill) actively refilled actuators per nozzle actuator is energized. The refill actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive ink The ink is held a slight * High refill rate, * Surface spill * Silverbrook, EP pressure positive pressure. therefore a high must be prevented 0771 658 A2 and After the ink drop is drop repetition rate * Highly related patent ejected, the nozzle is possible hydrophobic print applications chamber fills quickly head surfaces are * Alternative for:, as surface tension and required IJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20, IJ22-IJ45 operate to refill the nozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description Advantages Disadvantages Examples Long inlet The ink inlet channel * Design simplicity * Restricts refill * Thermal ink jet channel to the nozzle chamber * Operational rate * Piezoeiectric ink is made long and simplicity * May result in a jet relatively narrow, * Reduces relatively large chip * IJ42, IJ43 relying on viscous crosstalk area drag to reduce inlet * Only partially back-flow. effective Positive ink The ink is under a * Drop selection * Requires a * Silverbrook, EP pressure positive pressure, so and separation method (such as a 0771 658 A2 and that in the quiescent forces can be nozzle rim or related patent state some of the ink reduced effective applications drop already protrudes * Fast refill time hydrophobizing, or * Possible from the nozzle. both) to prevent operation of the This reduces the flooding of the following: IJ01- pressure in the nozzle ejection surface of IJ07, IJ09-IJ12, chamber which is the print head. IJ14, IJ16, IJ20, required to eject a IJ22,, IJ23-IJ34, certain volume of ink. IJ36-IJ41, IJ44 The reduction in chamber pressure results in a reduction in ink pushed out through the inlet. Baffle One or more baffles * The refill rate is * Design * HP Thermal Ink are placed in the inlet not as restricted as complexity Jet ink flow. When the the long inlet * May increase * Tektronix actuator is energized, method. fabrication piezoelectric ink jet the rapid ink * Reduces complexity (e.g. movement creates crosstalk Tektronix hot melt eddies which restrict Piezoelectric print the flow through the heads). inlet. The slower refill process is unrestricted, and does not result in eddies. Flexible flap In this method recently * Significantly * Not applicable to * Canon restricts disclosed by Canon, reduces back-flow most ink jet inlet the expanding actuator for edge-shooter configurations (bubble) pushes on a thermal ink jet * Increased flexible flap that devices fabrication restricts the inlet. complexity * Inelastic deformation of polymer flap resuits in creep over extended use Inlet filter A filter is located * Additional * Restricts refill * IJ04, IJ12, IJ24, between the ink inlet advantage of ink rate IJ27, IJ29, IJ30 and the nozzle flltration * May result in chamber. The filter * Ink filter may be complex has a multitude of fabricated with no construction small holes or slots, additional process restricting ink flow. steps The filter also removes particies which may block the nozzle. Small inlet The ink inlet channel * Design simplicity * Restricts refill * IJ02, IJ37, IJ44 compared to the nozzle chamber rate to nozzle has a substantially * May result in a smaller cross section relatively large chip than that of the nozzle area resulting in easier ink * Only partially egress out of the effective nozzle than out of the inlet. Inlet shutter A secondary actuator * Increases speed * Requires separate * IJ09 controls the position of of the ink-jet print refill actuator and a shutter, closing off head operation drive circuit the ink inlet when the main actuator is energized. The inlet is The method avoids the * Back-flow * Requires careful * IJ01, IJ03, IJ05, located problem of inlet back- problem is design to minimize IJ06, IJ07, IJ10, behind the flow by arranging the eliminated the negative IJ11, IJ14, IJ16, ink-pushing ink-pushing surface of pressure behind the IJ22, IJ23, IJ25, surface the actuator between paddle IJ28, IJ31, IJ32, the inlet and the IJ33, IJ34, IJ35, nozzle. IJ36, IJ39, IJ40, IJ41 Part of the The actuator and a * Significant * Small increase in * IJ07, IJ20, IJ26, actuator wall of the ink reductions in back- fabrication IJ38 moves to chamber are arranged flow can be complexity shut off the so that the motion of achieved inlet the actuator closes off * Compact designs the inlet. possible Nozzle In some configurations * Ink back-flow * None related to * Silverbrook, EP actuator of ink jet, there is no problem is ink back-flow on 0771 658 A2 and does not expansion or eliminated actuation related patent result in ink movement of an applications back-flow actuator which may * Valve-jet cause ink back-flow * Tone-jet through the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages Examples Normal All of the nozzles are ♦ No added ♦ May not be ♦ Most ink jet nozzle firing fired periodically, complexity on the sufficient to systems before the ink has a print head displace dried ink ♦ IJ01, IJ02, IJ03, chance to dry. When IJ04, IJ05, IJ06, not in use the nozzles IJ07, IJ09, IJ10, are sealed (capped) IJ11, IJ12, IJ14, against air. IJ16, IJ20, IJ22, The nozzle firing is IJ23, IJ24, IJ25, usually performed IJ26, IJ27, IJ28, during a special IJ29, IJ30, IJ31, clearing cycle, after IJ32, IJ33, IJ34, first moving the, print IJ36, IJ37, IJ38, head to a cleaning IJ39, IJ40,, IJ41, station. IJ42, IJ43, IJ44,, IJ45 Extra In systems which heat ♦ Can be highly ♦ Requires higher ♦ Silverbrook, EP power to the ink, but do not boil effective if the drive voltage for 0771 658 A2 and ink heater it under normal heater is adjacent to clearing related patent situations, nozzle the nozzle ♦ May require applications clearing can be larger drive achieved by over- transistors powering the heater and boiling ink at the nozzle. Rapid The actuator is fired in ♦ Does not require ♦ Effectiveness ♦ May be used success-ion rapid succession. In extra drive circuits depends with: IJ01, IJ02, of actuator some conflgarations, on the print head substantially upon IJ03, IJ04, IJ05, pulses this may cause heat ♦ Can be readily the configuration of IJ06, IJ07, IJ09, build-up at the nozzle controlled and the inkjet nozzle IJ10, IJ11, IJ14, which boils the ink, initiated by digital IJ16, IJ20, IJ22, clearing the nozzle. In logic IJ23, IJ24, IJ25, other situations, it may IJ27, IJ28, IJ29, cause sufficient IJ30, IJ31, IJ32, vibrations to dislodge IJ33, IJ34, IJ36, clogged nozzles. IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where an actuator is ♦ A simple ♦ Not suitable ♦ May be used power to not normally driven to solution where where there is a with: IJ03, IJ09, ink pushing the limit of its motion, applicable hard limit to IJ16, IJ20, IJ23, actuator nozzle clearing may be actuator movement IJ24, IJ25, IJ27, assisted by providing IJ29, IJ30, IJ31, an enhanced drive IJ32, IJ39, IJ40, signal to the actuator. IJ41, IJ42, IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is ♦ A high nozzle ♦ High ♦ IJ08, IJ13, IJ15, resonance applied to the ink clearing capability implementation cost IJ17, IJ18, IJ19, chamber. This wave is can be achieved if system does not IJ21 of an appropriate ♦ May be already include an amplitude and implemented at very acoustic actuator frequency to cause low cost in systems sufficient force at the which already nozzle to clear include acoustic blockages. This is actuators easiest to achieve if the ultrasonic wave is at a resonant frequency of the ink cavity. Nozzle A microfabricated ♦ Can clear ♦ Accurate ♦ Silverbrook, EP clearing plate is pushed against severely clogged mechanical 0771 658 A2 and plate the nozzles. The plate nozzles alignment is related patent has a post for every required applications nozzle A post moves ♦ Moving parts are through each nozzle, required displacing dried ink. ♦ There is risk of damage to the nozzles ♦ Accurate fabrication is required Ink The pressure of the ink ♦ May be effective ♦ Requires ♦ May be used pressure is temporarily where other pressure pump or with all IJ series ink pulse increased so that ink methods cannot be other pressure jets streams from aIl of the used actuator nozzles. This may be ♦ Expensive used in conjunction ♦ Wasteful of ink with actuator energizing. Print head A flexible ‘blade’ is ♦ Effective for ♦ Difficult to use if ♦ Many ink jet wiper wiped across the print planar print head print head surface is systems head surface. The surfaces non-planar or very blade is usually ♦ Low cost fragile fabricated from a ♦ Requires flexible polymer, e.g. mechanical parts rubber or synthetic ♦ Blade can wear elastomer. out in high volume print systems Separate A separate heater is ♦ Can be effective ♦ Fabrication ♦ Can be used with ink boiling provided at the nozzle where other nozzle complexity many IJ series ink heater although the normal clearing methods jets drop e-ection cannot be used mechanism does not ♦ Can be require it. The heaters implemented at no do not require additional cost in individual drive some ink jet circuits, as many configurations nozzles can be cleared simultaneously, and no imaging is required.

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages Examples Electro- A nozzle plate is ♦ Fabrication ♦ High ♦ Hewlett Packard formed separately fabricated simplicity temperatures and Thermal Ink jet nickel from electroformed pressures are nickel, and bonded to required to bond the print head chip. nozzle plate ♦ Minimum thickness constraints ♦ Differential thermal expansion Laser Individual nozzle ♦ No masks ♦ Each hole must ♦ Canon Bubblejet ablated or holes are ablated by an required be individually ♦ 1988 Sercel et drilled intense UV laser in a ♦ Can be quite fast formed al., SPIE, Vol. 998 polymer nozzle plate, which is ♦ Some control ♦ Special Excimer Beam typically a polymer over nozzle profile equipment required Applications, pp. such as polyimide or is possible ♦ Slow where there 76-83 polysulphone ♦ Equipment are many thousands ♦ 1993 Watanabe required is relatively of nozzles per print et al., U.S. Pat. No. low cost head 5,208,604 ♦ May produce thin burrs at exit holes Silicon A separate nozzle ♦ High accuracy is ♦ Two part ♦ K. Bean, IEEE micro- plate is attainable construction Transactions on machined micromachined from ♦ High cost Electron Devices, single crystal silicon, ♦ Requires Vol. ED-25, No. 10, and bonded to the precision alignment 1978, pp 1185-1195 print head wafer. ♦ Nozzles may be ♦ Xerox 1990 clogged by adhesive Hawkins et al., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries ♦ No expensive ♦ Very small ♦ 1970 Zoltan U.S. capillaries are drawn from glass equipment required nozzle sizes are Pat. No. 3,683,212 tubing. This method ♦ Simple to make difficult to form has been used for single nozzles ♦ Not suited for making individual mass production nozzles, but is difficult to use for bulk manufacturing of print heads with thousands of nozzles. Monolithic, The nozzle plate is ♦ High accuracy ♦ Requires ♦ Silverbrook, EP surface deposited as a Iayer (<1 μm) sacrificial layer 0771 658 A2 and micro- using standard VLSI ♦ Monolithic under the nozzle related patent machined deposition techniques. ♦ Low cost plate to form the applications using VLSI Nozzles are etched in ♦ Existing nozzle chamber ♦ IJ01, IJ02, IJ04, litho- the nozzle plate using processes can be ♦ Surface may be IJ11, IJ12, IJ17, graphic VLSI lithography and used fragile to the touch IJ18, IJ20, IJ22, processes etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, JJ43, IJ44 Monolithic, The nozzle plate is a ♦ High accuracy ♦ Requires long ♦ IJ03, IJ05, IJ06, etched buried etch stop in the (<1 μm) etch times IJ07, IJ08, IJ09, through wafer. Nozzle ♦ Monolithic ♦ Requires a IJ10, IJ13, IJ14, substrate chambers are etched in ♦ Low cost support wafer IJ15, IJ16, IJ19, the front of the wafer, ♦ No differential IJ21, IJ23, IJ25, and the wafer is expansion IJ26 thinned from the back side. Nozzles are then etched in the etch stop layer. No nozzle Various methods have ♦ No nozzles to ♦ Difficult to ♦ Ricoh 1995 plate been tried to eliminate become clogged control drop Sekiya et al U.S. the nozzles entirely, to position accurately Pat. No. 5,412,413 prevent nozzle ♦ Crosstalk ♦ 1993 Hadimioglu clogging. These problems et al EUP 550,192 include thermal bubble ♦ 1993 Elrod et al mechanisms and EUP 572,220 acoustic lens mechanisms Trough Each drop ejector has ♦ Reduced ♦ Drop firing ♦ IJ35 a trough through manufacturing direction is sensitive which a paddle moves. complexity to wicking. There is no nozzle ♦ Monolithic plate. Nozzle slit The elimination of ♦ No nozzles to ♦ Difficult to ♦ 1989 Saito et al instead of nozzle holes and become clogged control drop U.S. Pat. No. 4,799,068 individual replacement by a slit position accurately nozzles encompassing many ♦ Crosstalk actuator positions problems reduces nozzle clogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages Examples Edge Ink flow is along the ♦ Simple ♦ Nozzles limited ♦ Canon Bubblejet (‘edge surface of the chip, construction to edge 1979 Endo et al GB shooter’) and ink drops are ♦ No silicon ♦ High resolution patent 2,007,162 ejected from the chip etching required is difficult ♦ Xerox heater-in- edge ♦ Good heat ♦ Fast color pit 1990 Hawkins et al sinking via substrate printing requires U.S. Pat. No. 4,899,181 ♦ Mechanically one print head per ♦ Tone-jet strong color ♦ Ease of chip handing Surface Ink flow is along the ♦ No bulk silicon ♦ Maximum ink ♦ Hewlett-Packard (‘roof surface of the chip, etching required flow is severely TIJ 1982 Vaught et al shooter’) and ink drops are ♦ Silicon can make restricted U.S. Pat. No. 4,490,728 ejected from the chip an effective heat ♦ IJ02, IJ11, IJ12, surface, normal to the sink IJ20, IJ22 plane of the chip. ♦ Mechanical strength Through Ink flow is through the ♦ High ink flow ♦ Requires bulk ♦ Silverbrook, EP chip, chip, and ink drops are ♦ Suitable for silicon etching 0771 658 A2 and forward ejected from the front pagewidth print related patent (‘up surface of the chip. heads applications shooter’) ♦ High nozzle ♦ IJ04, IJ17, IJ18, packing density IJ24, IJ27-IJ45 therefore low manufacturing cost Through Ink flow is through the ♦ High ink flow ♦ Requires wafer ♦ IJ01, IJ03, IJ05, chip, chip, and ink drops are ♦ Suitable for thinning IJ06, IJ07, IJ08, reverse ejected from the rear pagewidth print ♦ Requires special IJ09, IJ10, IJ13, (‘down surface of the chip. heads handling during IJ14, IJ15, IJ16, shooter’) ♦ High nozzle manufacture IJ19, IJ21, IJ23, packing density IJ25, IJ26 therefore low manufacturing cost Through Ink flow is through the ♦ Suitable for ♦ Pagewidth print ♦ Epson Stylus actuator actuator, which is not piezoelectric print heads require ♦ Tektronix hot fabricated as part of heads several thousand melt piezoelectric the same substrate as connections to drive inkjets the drive transistors. circuits ♦ Cannot be manufactured in standard CMOS fabs ♦ Complex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Water based ink which ♦ Environmentally ♦ Slow drying ♦ Most existing ink dye typically contains: friendly ♦ Corrosive jets water, dye, surfactant, ♦ No odor ♦ Bleeds on paper ♦ All IJ series ink humectant, and ♦ May jets biocide. strikethrough ♦ Silverbrook, EP Modern ink dyes have ♦ Cockles paper 0771 658 A2 and high water-fastness, related patent light fastness applications Aqueous, Water based ink which ♦ Environmentally ♦ Slow drying ♦ IJ02, IJ04, IJ21, pigment typically contains: friendly ♦ Corrosive IJ26, IJ27, IJ30 water, pigment, ♦ No odor ♦ Pigment may ♦ Silverbrook, EP surfactant, humectant, ♦ Reduced bleed clog nozzles 0771 658 A2 and and biocide. ♦ Reduced wicking ♦ Pigment may related patent Pigments have an ♦ Reduced clog actuator applications advantage in reduced strikethrough mechanisms ♦ Piezoelectric ink- bleed, wicking and ♦ Cockles paper jets strikethrough. ♦ Thermal ink jets (with significant restrictions) Methyl MEK is a highly ♦ Very fast drying ♦ Odorous ♦ All IJ series ink Ethyl volatile solvent used ♦ Prints on various ♦ Flammable jets Ketone for industrial printing substrates such as (MEK) on difficult surfaces metals and plastics such as aluminum cans. Alcohol Alcohol based inks ♦ Fast drying ♦ Slight odor ♦ All IJ series ink (ethanol, 2- can be used where the ♦ Operates at sub- ♦ Flammable jets butanol, printer must operate at freezing and others) temperatures below temperatures the freezing point of ♦ Reduced paper water. An example of cockle this is in-camera ♦ Low cost consumer photographic printing. Phase The ink is solid at ♦ No drying time- ♦ High viscosity ♦ Tektronix hot cbange room temperature, and ink instantly freezes ♦ Printed ink melt piezoelectric (hot melt) is melted in the print on the print medium typically has a ink jets head before jetting. ♦ Almost any print ‘waxy’ feel ♦ 1989 Nowak Hot melt inks are medium can be used ♦ Printed pages U.S. Pat. No. 4,820,346 usually wax based, ♦ No paper cockle may ‘block’ ♦ All IJ series ink with a melting point occurs ♦ Ink temperature jets around 80° C. After ♦ No wicking may be above the jetting the ink freezes occurs curie point of almost instantly upon ♦ No bleed occurs permanent magnets contacting the print ♦ No strikethrough ♦ Ink heaters medium or a transfer occurs consume power roller. ♦ Long warm-up time Oil Oil based inks are ♦ High solubility ♦ High viscosity: ♦ All IJ series ink extensively used in medium for some this is a significant jets offset printing. They dyes limitation for use in have advantages in ♦ Does not cockie inkjets, which improved paper usually require a characteristics on ♦ Does not wick low viscosity. Some paper (especially no through paper short chain and wicking or cockle). multi-branched oils Oil soluble dies and have a sufficiently pigments are required. low viscosity. ♦ Slow drying Micro- A microemulsion is a ♦ Stops ink bleed ♦ Viscosity higher ♦ All IJ series ink emulsion stable, self forming ♦ High dye than water jets emulsion of oil, water, solubility ♦ Cost is slightly and surfactant. The ♦ Water, oil, and higher than water characteristic drop size amphiphilic soluble based ink is less than 100 nm, dies can be used ♦ High surfactant and is determined by ♦ Can stabilize concentration the preferred curvature pigment required (around of the surfactant. suspensions 5%) 

What is claimed is:
 1. A recyclable, one-time use, instant printing, digital camera comprising: a chassis; an ink cartridge unit supported on said chassis, the ink cartridge unit including a replenishable ink supply means and a pagewidth print head; a roll of print media rotatably and releasably mounted on said chassis, said print head printing a sensed image on said print media as the print media moves past the print head prior to ejection from the camera body; a platten unit mounted adjacent said print head for supporting the print media as it moves past the print head; image sensor and control circuitry connected to said print head for sensing said image for printing by said print head; and an outer casing for enclosing said chassis, ink cartridge unit, said print media, said platten unit and said circuitry.
 2. A camera as claimed in claim 1 further comprising a cutting unit which traverses said print media so that, after printing of an image on said print media that part of the print media containing the image can be separated from a remainder of the print media.
 3. A camera as claimed in claim 2 wherein said cutting unit is mounted on said platten unit.
 4. A camera as claimed in claim 1 wherein said platten unit includes a print head recapping unit for capping said print head when not in use.
 5. A camera as claimed in claim 1 further comprising a plurality of pinch rollers for decurling said print media.
 6. A recyclable, one-time use, instant printing, digital camera comprising: a chassis; an image sensing means supported on said chassis for sensing an image; a pagewidth print head supported on said chassis for printing said sensed image; an ink supply unit arranged on the chassis, the unit containing a replenishable ink supply means for supplying ink to the print head; and a replaceable supply of print media releasably carried on the chassis, the print media being fed past the print head in use, to enable said sensed image to be printed on the print media, the ability to replenish the ink supply means and to replace the supply of print media rendering the camera recyclable.
 7. A camera as claimed in claim 6 in which the ink supply unit includes a plurality of ink supply channels for enabling full color printing to be effected by the print head, the ink supply channels being in communication with access ports for enabling refilling of the channels to be effected.
 8. A camera as claimed in claim 7 in which each channel includes a damping means for damping movement of the ink in said channel.
 9. A camera as claimed in claim 7 in which the access ports are closed off by a closure member.
 10. A camera as claimed in claim 6 in which the print media is in the form of a print roll which is rotatably carried on the chassis, the camera including a guide means for guiding movement of the print media, as it is fed from the roll, past the print head.
 11. A camera as claimed in claim 10 in which the guide means includes a decurling means which assists in decurling the print media as it is fed from the roll.
 12. A camera as claimed in claim 10 in which the guide means is releasably supported on the chassis so that it can be removed to effect replenishment of the print media.
 13. A camera as claimed in claim 10 in which the guide means includes a capping means for capping the print head when said print head is not in use.
 14. A camera as claimed in claim 10 which includes a power supply means, the power supply means being replaceable and being housed within the print roll for rendering the camera compact.
 15. A camera as claimed in claim 6 which includes a camera body which is of a recyclable material. 